Quaternary ammonium bisulfites,sulfites or pyrosulfites as developer preservatives



United States Patent 10 3,549,370 QUATERNARY AMMONIUM BISULFITES, SUL- FITES OR PYROSULFITES AS DEVELOPER PRESERVATIVES Donald J. Sykes, Upper Saddle River, N.J., Harry Kroll, Warwick, R.I., and Theron R. Finch, Northvale, N.J., assiguors to Philip A. Hunt Chemical Corporation, Palisades Park, N.J., a corporation of Delaware No Drawing. Filed June 15, 1967, Ser. No. 646,176 Int. Cl. G03c 5/30, 5/38, 7/00 US. Cl. 96-55 24 Claims ABSTRACT OF THE DISCLOSURE A developing solution for silver halide gelatin layers, which solution includes a conventional developing agent or agents and other conventional constituents such as restrainers, anti-foggants, sequestrants, silver halide solvents and gelatin hardeners, and which for the preservative uses a quaternary ammonium bisulfite, sulfite or pyrosulfite of the formula:

in which each of R R R and R is selected from the class consisting of alkyls of one to four carbon atoms,

hydroxyalkyls of two to four carbon atoms, benzyl and phenyl.

CROSS-REFERENCE TO RELATED APPLICATION ing such supported layers with a bath including as the preservative a substance selected from the group composed of quaternary ammonium bisulfites, sulfites, and pyrosulfites. Although not so specifically restricted, the invention presently finds its best commercial applicability in the developing of photographic gelatin layers.

The invention embraces the use of the foregoing chemical compositions (a) in working solutions of photographic developers, (b) in liquid developer concentrates, that is to say, liquid compositions which are intended to be diluted, as with Water, to form working solutions, (c) in liquid replenishers for developers, these constituting solutions more concentrated than Working solutions and which are intended to be added to working solutions that are at least in part exhausted so as to bring them back to working strength, (d) in combined developer/fixers of working strengths, these constituting socalled monobaths in which both developing and fixing takes place, and (e) in monobath concentrates which are intended to be diluted, as with water, to form monobath Working solutions.

It is customary in photographic processing baths, and particularly so in photographic developing solutions, to employ preservatives, as, for example, for preventing oxidation of the developing agents. The preservatives heretofore conventionally employed were alkali metal sulfites, alkali metal bisulfites, hydroxyalkylamine-sulfur dioxide addition products, and ascorbic acid and its isomers. The alkali metal sulfites and/or alkali metal bisul fites are effective preservatives but are of limited solubility in ice water. Developers which contain high proportions of hydroxyalkylamine-sulfur dioxide addition products tended to have a high viscosity and hence were difiicult to pour and measure accurately and to mix smoothly and easily with diluents such as Water.

Moreover, some developers containing such prior art preservatives tended to induce a reaction between the preservatives and other constituents of the bath, so that the developers solutions were not highly stable. Specifically, there tended to be a reaction between such prior art preservatives and prior art gelatin hardening agents,

viz, aldehydes and dialdehydes.

It is an object of the present invention to provide a silver halide photographic processing preservative for developers which is not subject to any of the foregoing drawbacks and which accordingly will provide liquid concentrates and working solutions of all types that are highly stable, that do not tend to react with other constituents of the developers and that are sufficiently nonvis'c'ous to pour accurately and with ease and to mix smoothly and readily with diluents such as Water.

According to the instant invention all of these disadvantages are overcome by employing as a preservative quaternary ammonium bisulfites, sulfites and pyrosulfites.

The quaternary ammonium bisulfites sulfites and pyrosulfites of the present invention have the following generalized structure:

in which each of R R R and R is selected from the class consisting of alkyl of 1 to 4 carbon atoms, hydroxyalkyls, i.e. HO(CH where nequals 2, 3, or 4 carbon atoms, benzyl and phenyl.

The following are specific examples of various quaternary amonium bisulfites, sulfites and pyrosulfites which are useful as preservatives in developers for photographic silver halide layers:

(1) Tetramethyl ammonium bisulfite (CH NHSO (2) Tetramethyl ammonium sulfite (3) Tetramethyl ammonium pyrosulfite (4) Tetramethyl ammonium bisulfite (CH CH NHSO (5 Tetraethyl ammonium sulfite (6) Tetraethyl ammonium pyrosulfite a z) 4 2 2 (7) N,N,N-triskis (2-hydroxyethyl), N-methyl ammonium bisulfite (HOCH2CH2)3NHSO3 (8) N,N-bis' (2-hydroxyethyl), N,N-dimethyl ammonium bisulfite CH3 (HOCHzCHflzlLHSCh (1H, (9) N,N,N-triskis (ethyl), N-methyl ammonium bisulfite CH; (CZHQfl IHSOB (10) N,N,N-triskis methyl, N-phenyl ammonium bisulfite o s (CHQaIkHSOg (11) N,N,N-triskis methyl, N-benzyl ammonium bisulfite CeHsCHg (CHmNHs o;

(12) N,N,N triskis (methyl), N (2 hydroxyethyl) ammonium bisulfite HOCHzCHz (CHa)aNHSOa (13) N,N,N,N-tetrakis (2-hydroxyethyl) ammonium bisulfite (HOCH CH NHSO Compounds illustrated in Examples 7 through 13 can be employed as the pyrosulfite or sulfite in place of the bisulfite without altering the scope or spirit of the invention.

The foregoing compounds can be prepared by passing gaseous or liquid sulfur dioxide through a solution of the corresponding quaternary ammonium hydroxide solution. For example, if. the compound to be prepared is tetramethyl ammonium pyrosulfite the solution is of tetramethyl ammonium hydroxide. If the compound to be prepared is N,N,N-triskis (Z-hydroxyethyl), N-methyl ammonium pyrosulfite, the solution is of N,N,N-triskis (Z-hydroxyethyl), N-methyl ammonium hydroxide, etc.

Quaternary ammonium bisulfites, sulfites and pyrosulfites such as have been described above are well known to the art. However, by way of illustration, there follows a description of a process for manufacturing tetramethyl ammonium pyrosulfite.

Introduce one mole of tetramethyl ammonium hydroxide dissolved in methanol, e.g., a 24% solution of tetramethyl ammonium hydroxide in methanol, into a glass reaction flask fitted with a gas-distributing apparatus, e.g., a bubbling ring at the bottom, a stirrer and a thermometer. While stirring the tetramethyl ammonium hydroxide-methanol solution, gaseous sulfur dioxide is bubbled through the gas distributor into the bottom of the reaction flask containing he methanol solution of tetramethyl ammonium hydroxide. The reaction is carried out at atmospheric pressure. The reaction flask should be cooled to prevent the temperature from rising beyond 60 C. Any mole ratio of sulfur dioxide to quaternary ammonium hydroxide can be employed, varying, for example, as widely as from one-thousandth part of sulfur dioxide to one part of quaternary ammonium hydroxide, to equal parts of each.

The following equation illustrates a possible reaction:

solved in water with the consequent formation of tetramethyl ammonium bisulfiite. The following equation illustrates the reaction:

When the tetramethyl ammonium bisulfite is dissolved in an alkaline aqueous solution, it is converted into the sulfite, namely, tetramethyl ammonium sulfite.

The foregoing is simply one exemplification production method. Any other suitable production method may be employed.

The quaternary ammonium bisulfite, sulfite and pyrosulfiite novel preservative compounds of the present invention have the same stabilizing effect for photographic developing agents, to wit, inhibition of oxidation, as is conventionally supplied by alkali metal sulfites, bisulfites, hydroxyalkylamine sulfur dioxide addition products, ascorbic acid and its isomers presently known in the art, and said novel preservative compounds are used, pursuant to the present invention, to formulate stable photographic developers, e.g., working solutions and liquid concentrates, that are stable against oxidation, such developers being inclusive of a photographic developing agent, and including conventional alkali-buffer systems, such, for instance, as quaternary ammonium hydroxides, alkali metal carbonates, tetraborates, metaborates, hydroxides and the family of hydroxyalkylamines, either separately or in combination.

Thus, the present invention embraces the use of these novel preservative compounds in photographic treating solutions where they may act as preservatives in combination with all manners of known alkalis and alka i buffer systems.

The present invention includes the use with the aforesaid novel preservative compounds of all developing agents, particularly silver halide developing agents, which are well known to the art. An exemplificative partial list of photographic developing agents suitable for use separately or in combination with the new novel preservative compounds in working baths, concentrates and monobaths includes: hydroquinone, chloro-hydroquinone, bromo-hydroquinone, p-phenylene-diamine and all its derivatives, n-monomethyl-p-aminophenol sulfate, l-phenyl- 3-pyrazolidone and all its derivatives including 4,4-dimethyl-1-phenyl-3-pyrazolidone. Other developing agents can be employed without altering the scope of this invention. Developers so formulated may contain the known photographic developer addenda, i.e., restrainers; viz alkali metal chlorides, alkali metal bromides, alkali metal iodides; antifoggants: viz. benzotriazole, S-methylbenzotriazole, 6-nitrobenzimidazole, l-phenyl-S-mercapto tetrazole, Z-anthraquinone-sulfonic acid; sequestering agents: viz ethylenediamine tetraacetic acid and sodium hexametaphosphate; silver halide solvents: viz alkali metal thiosulfate and thioglycolates: various co-solvents: viz diethylene glycol; and gelatin hardening agents; viz formaldehyde and glutaraldehyde, as well as their bisulfate adducts.

It should be mentioned that processing compositions, and particularly developing compositions including developing agents, are not restricted solely to use with gelatin layers. They may be employed equally well, for instance, in silver-halide containing gelatin layers including gelatin extenders, such as carboxymethylated soy protein, or succinoylated hydroxyethyl cellulse, which replace a part of the gelatin in the photographic emulsion layer.

It has been found by employing combinations of the foregoing constitutents, to wit, the developing agents, the

novel preservative compounds, alkali buffer systems, and, if desired, restrainers, anti-foggants, sequestering agents, silver halide solvents, co-solvents, and gelatin hardening agents, that high quality photographic developers and developer/fixers with excellent stability have been prepared.

It has been ascertained that by utilizing the present invention, the quaternary ammonium bisulfite, sulfite and pyrosulfite novel preservatives enable developers and developer/fixers to be formulated that can be packaged and stored in highly concentrated liquid forms. This is the result of the high degree of solubility of quaternary ammonium bisulfites, sulfites and pyrosulfites in water in comparison with the lesser solubility of conventional alkali metal sulfites or bisulfites and other prior art preservatives.

Quaternary ammonium bisulfites, sulfites and pyrosulfites allow for greater developer system solubility, i.e., the solubility of the system including the preservative and developing agents and hardener and/or anti-foggant, and/ or sequestrants, etc.

Concentrates of developers and of developer/fixers embodying the present invention, i.e., formulated to include as the preservative quaternary ammonium bisulfites, sulfites and pyrosulfites, are of a low order of viscosity that is particularly conducive to trouble-free mixing and is quite unlike some known concentrates of developers and developer/fixers employing as the preservative agent hydroxyalkylamine-sulfur dioxide addition products. These latter are considerably more viscous. For example, a developer concentrate containing an alkanolamine sulfur dioxide addition product as the preservative in an amount of g. per ml. of developer concentrate, along with proportionate amounts of developing agent and buffering agent, has a viscosity of 5250 centipoises at room temperature. This obviously makes preparation of a working developer bath extremely difiicult.

The novel preservative compounds of the present invention are highly compatible with the other constitutents of developing compositions, i.e., are inert thereto. In particular, one of the advantages of employing quaternary ammonium bisulfites, sulfites and pyrosulfites is that in combination with known gelatin hardening agents, namely, aldehydes and dialdehydes, a particularly stable developer concentrate and/or working solution results.

It has been mentioned above that the novel preservative compound of the present invention can be used effectively in connection with aldehyde and dialdehyde gelatin hardening agents to form a particularly stable developer concentrate and/or working developer solution. Specific aldehydes and dialdehydes useful in the present invention and mentioned by way of example are formaldehyde, glyoxal, glutaraldehyde, succinic dialdehyde, maleic dialdehyde, their derivatives and their bisulfite addition products.

The following examples will illustrate the use, in accordance with the invention, of quaternary ammonium bisulfites, sulfites and pyrosulfites in a wide variety of actual developer formulations including many types of different systems in varying proportions sufiicient to act as a preservative for this developing agent.

EXAMPLE I Mix together the following constituents:

Water-700 m1. Tetramethyl ammonium bisulfite solution, i.e., 55

grams per 100 cc. of water solution)20.0 g. Hydroquinone (developing agent)4.0 g. 1-phenyl-3-pyrazolidone (developing agent)0.l25 g. Buffer-alkali- Boric acid-20.0 g. Potassium hydroxide (90% )-18.6- g. Ethylenediamine tetraacetic acid (sequestering agent)- 1.0 g. Potassium bromide (restrainer)0.2 g.

After the foregoing has been throughly mixed enough additional water is added to make up 1000 ml. of solution.

The solution prepared as per Example I produces an excellent working developer for both film and paper. Eastman Kodak Plus-X Pan Film, at film having a gelatin silver halide emulsion layer is processed with the developer of Example I at 68 :F. for only 2 minutes to yield excellent results.

Eastman Kodak Kodabromide F-Z paper, a paper coated with a photographic gelatin containing silver bromide, is developed with the developer of Example I at 68 F. for 60 seconds to produce excellent results. Both the film and the paper are fixed in a rapid acid fixing bath for 3 minutes at 68 F. and are washed for 15 minutes at 68 F., then being dried in the normal manner. The developing solution of Example I can be packaged in any convenient way.

EXAMPLE II Water700 ml.

Tetramethyl ammonium pyrosulfite22.0 g. Hydroquinone5.0 g. 4-methyl-l-phenyl-3-pyrazolidone0.125 g. Potassium carbonate (monohydrated)20.0 g. Potassium bromide-0.2 g.

Potassium hydroxide4.4 g.

Water to 1000 ml.

The above prepared developer is extremely stable and well buffered. Plus-X Pan Film and Kodabromide F-2 paper are processed at 68 F. for 2 minutes, followed by fixing and washing as described in Example I.

EXAMPLE III Water-700 ml.

Ethylenediamine tetraacetic acid-2.0 g.

Tetramethyl ammonium bisulfite (55% solution)l3.4 g. Hydroquinone3.0 g.

1-phenyl-3-pyrazolidone1.0 g. 1-phenyl-5-mercapto-tetrazole0.02 g. 2-methylaminoethanol16.7 g.

Water to 1000 ml.

This formulation will effectively develop photographic printing paper similar to Kodabromide F-2 at 68 F. for 1 minute. Fixing and washing is as described in Example I.

EXAMPLE IV Water600 ml.

Ethylenediamine tetraacetic acid1.0 g. Tetramethyl ammonium bisulfite (55% solution)58.0 g. Hydroquinone--20.0 g.

Glutaraldehyde (50% )8.0 g. 4-methyl-l-phenyl-3-pyrazolidone--2.0 g. BenZotriazole-0.50 g. 6-nitrobenzimidazole--0.20 g.

Boric acid-28.0 g.

Potassium bromide-8.0 g.

Potassium hydroxide )3l.0 g. Water to 1500 ml.

Thisstable, hardening formulation will develop both double and single coated X-ray filmin 70 seconds at 90 F. The developed X-rays are fixed in a standard, rapid, acid ammonium thiosulfate fixer, such as is used for automatic processing of X-ray film, for 35 seconds and washed for 60 seconds at 90 F. and dried.

EXAMPLE V Water-700 ml.

Ethylenediamine tetraacetic acid1.0 g.

Tetramethyl ammonium bisulfite (55 solution)15.0 g. Hydroquinone4.0 g. 4-methyl-1-phenyl-3-pryrazolidone1.0 g.

Potassium carbonate-15.0 g.

Potassium bromide0.25 g.

ample II.

S-methylbenzotriazole-0.05 g. Water to 1000 ml.

The developer prepared from Example V will develop Plus-X Pan film to a gamma of 0.82 in minutes at 68. F. Kodabromide F-2 paper is developed in 2 minutes at 68 F. Both materials are fixed in a rapid acid fixer for 3 minutes and washed in running water for 15 minutes at 68 F. and dried in any conventional manner.

EXAMPLE VI Water-600 ml.

Ethylenediamine tetraacetic acid2.0 g.

Tetramethyl ammonium bisulfite (55% solution)--30.0 g. Hydroquinone10.0 g.

1-phenyl-3-pyrazolidone-2.5 g.

Sodium thiosulfate (anhydrous)-50.0 g. 1-phenyl-5-mercapto-tetrazole0.01 g.

Sodium hydroxide10.0 g.

Water to 1000 ml.

The foregoing combined developer/fixer (monobath) will completely process film similar to Plux-X Pan film in 8 minutes at 68 F. After processing, the film is washed for 5-10 minutes at 68 F. and dried. Excellent image quality results.

EXAMPLE VII Water-700 ml.

Tetramethyl ammonium bisulfite 5 5 solution)l0.0 g.

Hydroquinone3.0 g.

1-phenyl-3-pyrazolidone--0.5 g.

Tetramethyl ammonium hydroxide (24% solution) Water to 1000 ml.

This bath will develop miniature film, such as Plus-X Pan film in 10 minutes at 68 F. to a gamma of 0.65. Fixing, washing and drying are done in the conventional manner.

The chemical nature of quaternary ammonium bisulfite compounds allows formulation of packaged prepared de- 'velopers or developer/fixers in convenient, highly concentrated forms. The following examples demonstrate this additional advantage of the invention.

EXAMPLE VIII Part A Tetramethyl ammonium bisulfite (55 solution)40.0 g. Hydroquinone-5.0 g. 4-methyl-1-phenyl-3-pyrazolidone0.125 g. Water to 40 ml.

Viscosity equals 17.5 centipoises at 68 F.

Part B Water20 ml. Potassium carbonate20.0 g. Potassium bromide-0.2 g. Potassium hydroxide-4.4 g. Water to 40 ml.

The two above concentrates, A plus B, when combined and diluted to 1 liter with tap water Will develop film and paper yielding results identical to those described in Ex- EXAMPLE D( Part A Tetramethyl ammonium bisulfite (55% solution)13.4 g. Hydroquinone-3.0 g. 1-phenyl-5-mercapto-tetrazole+-0.02 g. 1phenyl-3-pyrazolidone-1.0 g.

Water to 30.0 ml.

Part B 2-methylamin0ethano116.7 g. Ethylenediamine tetraacetic acid-2.0 g. Water to 30.0 ml.

The above prepared concentrates, Part A plus Part B, when combined and diluted with tap 'water to 1000 ml. for use, yield sensitometric results on Kodabromide F-2 paper identical to results obtained with Example HI.

EXAMPLE X Part A Part C Methyl Cellosolve15.0 ml. 4-methyl-1-phenyl-3-pyrazolidone-2.0 g. 6-nitrobenzimidazole-0.2 g.

Part A plus B and C when combined and diluted with tap water to 1500 ml. will produce a developer that will process X-ray film as is described in Example IV.

Other examples of working developers are:

EXAMPLE XI Water-700 ml.

N,N,N-triskis (methyl), N-(Z-hydroxyethyl) ammonium bisulfite (58% solution)-25.0 g.

Hydroquinone4.0 g.

1-phenyl-3-pyrazolidone-0.125 g.

Boric acid20.0 g.

Ethylenediamine tetraacetic acidl.0 g.

Potassium bromide0.2 g.

Potassium hydroxidel 8.2 g.

Water to 1000 ml.

The above described developer will develop Plus-X film in 2 minutes at 68 F. This is followed by conventional fixing, washing, and drying.

EXAMPLE XII Water-700 ml.

N-methyl, N,N,N-triskis (2-hydroxyethyl) ammonium bisulfite (51% solution)--25.0 g.

Hydroquinone4.0 g.

1-phenyl-3-pyrazolidone0.125 g.

Boric acid-20.0 g.

Ethylenediamine tetraacetic acid1.0 g.

Potassium bromide-02 g.

Potassium hydroxide-18.4 g.

Water to 1000 ml.

The developer produced above will develop Plus-X pan film in 2 minutes at 68 F. Conventional fixing, washing, and drying follow.

EXAMPLE XIH Tetraethyl ammonium bisulfite (38% solution)25.0 g. Hydroquinone5.0 g.

1-pheny1-3-pyrazolidone0.125 g.

Potassium carbonate-20.0 g.

Potassium bromide--0.2 g.

Potassium hydroxide0.8 g.

Water to 1000 ml.

This solution will develop Plus-X pan film in 2 minutes at a temperature of 68 F. Fixing, washing, and drying follow in the conventional manner.

To show the photographic properties of the aforementioned examples, the developing characteristics of most of them have been illustrated in the subsequent table in which various standard developing compositions have been given as examples of conventional photographic chemistry. The measured parameters do not necessarily show the relative merits of the various formulations. These parameters can be :varied at will by altering the individual formulations.

10 4. A method as set forth in claim 3 wherein the developing agent includes a mixture of hydroquinone and a compound selected from the class consisting of l-phenyl- 3 pyrazolidone, 4 methyl-1-phenyl-3-pyrazolidone, and 4,4-dimethyl-1-phenyl-3-pyrazolidone.

EXAMPLES OF PHOTO GRAPHIC EFFECTS ON KODABROMIDE F-2 PAPER NOTE: Developer D-72 is an Eastman Kodak developer containing sodium sulfite, hydroquinone, n-monomethyl-paminophenol sulfate (Metol), sodium carbonate and potassium bromide. One part by volume of D-72 is mixed with two parts by volume of water.

EXAMPLES OF PHOTOGRAPHIC EFFECTS ON PLUS-X PAN ROLL FILM Relative speed at density of Developing Developing Density Contrast 0.50 above Developer time, min. temp., F. base plus fog (gamma) base plus fog D- 7 68 0. 11 0. 76 85. D-76 10 68 0. 11 0. 88 115. 0 Example I 2 68 0. 10 0.76 70. 0 Example II 2 68 0. 10 0. 96 95. 0 Example V 68 0. 0. 82 130.0 Example VI 8 68 0. 07 0. 47 26. 0 Example VII- 10 68 0. 22 0. 65 70. 0 Example XI 2 68 0. 10 0. 72 60. 0 Example XII- 2 68 0t 09 0. 73 50. 0 Example XI1I 2 68 O. 14 0. 85 110. 0

NOTE: Developer D-76 is an Eastman Kodak developer and includes essentially the same constituents in varying proportions as D72, except that borax is substituted for sodium carbonate.

EXAMPLES OF PHOTOGRAPHIC EFFECTS ON EASTMAN KODAK BLUE BRAND X-RAY FILM Norm Developer D-19 is an Eastman Kodak developer and includes hydroquinone, sodium carbonate, sodium hydroxide, Metol and sodium sulfite,

This invention has been described in considerable detail with examples and references to specific formulation of both developer working solutions and prepared concentrates. It is understood that modifications and adjustments can easily be effected within the scope and spirit of this invention as described above and as defined in the following claims.

Having thus described our invention, we claim as new and desire to secure by Letters Patent:

1. A method of developing an exposed gelatin-silver halide photographic emulsion layer comprising treating the emulsion layer with an aqueous bath including a developing agent and a preservative constituting a compound selected from the class consisting of quaternary ammonium bisulfites, sulfites and pyrosulfites of the formulae:

R2 R2 R2 N 11803 N 803- and N 5205" R R3 R3 R4 R4 2 R4 2 in which each of R R R and R is selected from the class consisting of alkyls of l to 4 carbon atoms, hydroxyalkyls of 2 to 4 carbon atoms, benzyl and phenyl.

2. A method as set forth in claim 1 in which the developing agent includes a dihydroxybenzene.

3. A method as set forth in claim 1 wherein the developing agent includes a combination of a dihydroxybenzene and a 3-pyrazolidone.

5. A method as set forth in claim 1 wherein the developing agent includes at least two compounds selected from the class consisting of hydroquinone, chloro-hydroquinone, bromo-hydroquinone, p-phenylenediamine and derivatives thereof, n-monomethyl-p-aminophenol sulfate, and l-phenyl-3-pyrazolidone and derivatives thereof.

6. A method as set forth in claim 1 wherein the developing agent includes a substituted p-phenylenediamine color developing agent.

7. A method as set forth in claim 1 wherein the bath includes a silver halide solvent 8. A method as set forth in claim 1 wherein the bath includes a gelatin hardener selected from the class consisting of aldehydes and dialdehydes.

9. A method as set forth in claim 1 wherein the bath includes a buffer selected from the class consisting of hydroxides, carbonates, borates and hydroxyalkylamines.

10. A method as set forth in claim 1 wherein the bath is prepared by diluting in water a liquid aqueous concentrate containing a high proportion of a developing agent and a preservative selected from said class, the preservative on an S0 basis being present in at least equal molar ratio to the total number of mols of the developing agent.

11. A method as set forth in claim 1 wherein the preservative is tetramethyl ammonium bisulfite.

12. A method as set forth in claim 1 wherein the preservative is selected from the class consisting of (a) tetramethyl ammonium bisulfite, (b) tetramethyl ammonium sulfite, (c) tetramethyl ammonium pyrosulfite,

(d) tetraethyl ammonium bisulfite,

(e) tetraethyl ammonium sulfite,

(f) tetraethyl ammonium pyrosulfite,

(g) N,N,N-triskis (2-hydroxyethyl), N-methyl ammonium bisulfite,

(h) N,N-bis-(2-hydroxyethyl), N,N-dimethyl monium bisulfite,

(i) N,N,N-triskis (ethyl), N-methyl ammonium bisulfite,

(j) N,N,N-triskis methyl, N-benzyl ammonium bisul- N HS 03 N S 04" and N 520 Ra Ra R3 R4 R4 2 R4 2 in which each of R R R and R is selected from the class consisting of alkyls of 1 to 4 carbon atoms, hydroxyalkyls of 2 to 4 carbon atoms, benzyl and phenyl. 14. A developer as set forth in claim 13 in which the preservative is selected from the class consisting of (a) tetramethyl ammonium bisulfite,

(b) tetramethyl ammonium sulfite,

(c) tetramethyl ammonium pyrosulfite,

(d) tetraethyl ammonium bisulfite,

(e) tetraethyl ammonium sulfite,

(f) tetraethyl ammonium pyrosulfite,

(g) N,N,N-triskis (2-hydroxyethyl), N-methyl ammonium bisulfite,

(h) N,N-bis (2-hydroxyethyl), N,N-dimethyl ammonium bisulfite,

(i) N,N,N-triskis (ethyl), N-methyl ammonium bisulfite,

(j) N,N,N-triskis methyl, N-benzyl ammonium bisulfite,

(k) N,N,N-triskis methyl, N phenyl ammonium bisulfite, (l) N,N,N-triskis (methyl), N-(Z-hydroxyethyl) ammonium bisulfite, and

12 (m) N,N,N,N-tetrakis (Z-hydroxyethyl) ammonium bisulfite, and sulfites and pyrosulfites of compounds (h) through (m).

15. A developer as set forth in claim 13 in which the developing agent includes a dihydroxybenzene.

16. A developer as set forth in claim 13 in which the developing agent includes a combination of dihydroxybenzene and a 3-pyrazolidone.

17. A developer as set forthin claim 13 in which the developing agent includes a mixture of hydroquinone and a compound selected from the class consisting of lphenyl-3-pyrazolidone, 4-methyl-1-phenyl-3-pyrazolidone, and 4, 4-dimethyl-1-phenyl-3-pyrazolidone.

18. A developer as set forth in claim 13 in which the developing agent includes at least two compounds selected from the class consisting of hydroquinone, chlorohydroquinone, bromo-hydroquinone, p-phenylenediamine and derivatives thereof, n-monomethyl-p-aminophenol sulfate, and l-phenyl-3-pyrazolidone and derivatives thereof.

19. A developer as set forth in claim 13 in which the developing agent includes a substituted p-phenylenediamine color developing agent.

20. A developer as set forth in claim 13 which includes a silver halide solvent.

21. A developer as set forth in claim 13 which includes a gelatin hardener selected from the class consisting of aldehydes and dialdehydes.

22. A developer as set forth in claim 14 which includes a buffer selected from the class consisting of hydroxides, carbonates, borates and hydroxyalkylamines.

23. A developer as set forth in claim 14 which is a liquid concentrate containing a high proportion of a preservative selected from said class, the preservative on an S0 basis being present in at least equal molar ratio to the total number of mols of the developing agent.

24. A developer as set forth in claim 13 in which the preservative is tetramethyl ammonium bisulfite.

References Cited UNITED STATES PATENTS 2,030,336 2/1936 Ulrich et a1. 9666.4 3,022,168 2/ 1962 Stjarnkuist 96-664 FOREIGN PATENTS 958,678 5/1964 Great Britain 96-661 430,916 6/1935 Great Britain 9666.1

NORMAN G. TORCHIN, Primary Examiner M. F. KELLEY, Assistant Examiner U.S. Cl. X.R. 96--6l, 66.1, 66.4 

